It is known to dispense strapping from a coil of the material by pulling the material to unwind it from the coil. The coil of strapping material maybe wound onto a core having a width or thickness equal to the width of the strapping or onto a core having a width or thickness greater than the strapping and is traversed back and forth across the core during winding. Additionally, the inner diameter of the core or coil can vary greatly depending upon the type of material, the width of the strapping, the quantity of the strapping and the manufacture of the strapping. The removal of the strapping from the coil as desired has always presented many problems. It is desirable to support the coil for rotation to permit removal of the strapping by pulling the material from the coil. Many complex mandrills or reels for rotatably supporting coils of strapping have heretofore been devised in an attempt to accommodate coils of various thickness or of various inner diameters. However, these devices do not provide a solution to both the problem of supporting coils of various thickness and of various inner diameters, but rather only address one or the other, and tend to be difficult to operate and expensive to manufacture. Additionally, these devices require the coil or reel to be axially loaded onto the spindle for supporting the coil or reel.
Another problem exists when the strapping is pulled from the rotatably supported coil. The momentum of the coil of the material, especially caused by the initial force required to start the coil turning from rest, tends to result in overrunning. Overrunning, is a condition where the coil continues to rotate after the operator has stopped pulling on the strapping or where the operator cannot keep up with the rate at which it is unwound from the coil. Overrunning, in addition to an excess of strapping being unwound from the coil, can result in a looseness among the outer turns of the strapping which can cause the turns to become crossed, expand or enlarge beyond the diameter of the coil and bind the coil against rotation.
Many reel or coil braking devices have been proposed and used to prevent overrunning. While these devices provide braking and may prevent overrunning they create additional objectionable characteristics. Foremost, the prior braking devices operate to apply a constant braking force against the rotation of the coil or reel as the strapping is being pulled from the coil creating a drag opposing the operator's pull. The problem with applying a constant braking force is the weight of the coil is not taken into consideration. A full coil of strapping is substantially heavier than a coil that has had strapping removed. As strapping is removed from the coil, the weight of the coil is reduced, thereby reducing the coil momentum and the amount of braking force required to prevent overrunning. In the devices heretofore, the braking force is initially set for the weight of a full coil of strapping, and this force is not adjusted as the weight is reduced, resulting in an increasing amount of drag the operate must work against. In other words, while the braking force remains constant, the required force for braking is lowered as the weight of the coil is reduced as a result of a lower coil momentum, and as a result, the operator must pull harder against the brake to compensate for this reduced momentum.
Accordingly, there is a need for a strap dispenser apparatus that is adjustable to the thickness of the coil and is not limited to the inner diameter of the coil. Further, there is a need for a strap dispensing apparatus where the coil can be loaded either from the front, top or side and supported for rotation. Further, there is a needed for proportional braking of the coil to prevent overrunning.